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Topic: What really matters is the NET difference
Replies: 1   Last Post: Jun 14, 2014 1:58 PM

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Luis A. Afonso

Posts: 4,615
From: LIsbon (Portugal)
Registered: 2/16/05
What really matters is the NET difference
Posted: Jun 12, 2014 4:02 PM
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What really matters is the NET difference

A numerical illustration.
ONCE upon a time . . .
An industrial orchard was formed by 2 apple species. It was found that out of 1000 trees, species A, 53 were contaminated by a worm, 17 species B.
______
pA= 0.053, pB= 0.017
Pooled proportion: 70/2000= 0.035,
Z=(0.053-0.017)/sqrt(0.035*0.965*2/1000)=
0.036/ 0.00821888= 4.380
We conclude that there are a significant difference between species because p-value = 0.0000059 <0.05.
Now in order to get Z0=1.645, because prob. (Z0< 1.645) = 0.05, we perform:
(0.036-d)/sqrt =1.645,
d = 0.036-1.645*0.00821888= 0.02248
And the conclusion is: It was found that there is a 95% probability that d = 0.022 as the NET proportions difference between species A and B to be attacked.

This example proves that NHST could be pushed beyond the NILNULL that seems to be the greatest Psychologist´s concerns at all . . . They (possibly) were not educated at this direction, but has no excuse, at all, they never thought about as Professionals. Against all expectations they put in action a Taliban´s campaign to ban the NHST´s which is a serious, very serious action, the worse they could even carry on (and the stupidest, I should agree).
Luis A. Afonso



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